The embodiments disclosed hereinafter generally relate to methods for automated transmitting of data messages from an aircraft. In particular, the disclosed embodiments relate to methods for automatically transmitting data messages in response to a parameter attaining a value equal to or in excess of a trigger threshold.
Various digital datalink systems for transmission of messages between aircraft and ground stations via radio or satellite are known, including the Aircraft Communications Addressing and Reporting System (ACARS). ACARS-equipped aircraft have an avionics computer called an ACARS. Management Unit (MU), which is directly interfaced to a Control Display Unit (CDU) in the cockpit. There is a datalink interface between the ACARS MU and the flight management system (FMS). Each airline has its own unique ACARS application operating on its aircraft. In addition, since each airline's computers are different, the content and format of messages sent by an ACARS MU differs for each airline.
An ACARS message typically comprises a header containing an aircraft identifier, a payload containing aircraft calculated and measured data and a cyclic redundancy check. The message is constructed in a user message format specified by the recipient of the message and in accordance with a dynamically settable user configuration stored in a subscriber database. This user configuration specifies which functions or processes are running in parallel, and also defines connections to receive and transmit the data. The user configuration also specifies the behavior of the application. The user message format generally pertains to the order and type of data and usually does not encompass the behavior of the application.
ACARS is a system for transmission of data messages between aircraft and ground stations via radio (VHF or HF) or satellite. ACARS messages are transmitted to and from aircraft before, during and after flights. For example, the aircraft sends in-flight reports on position, altitude, speed, outside temperature, wind, fuel, engine performance, etc over AGARS. The system automatically selects the communication means based on available links and avionics selection policies, which may take into consideration factors such as cost, performance and availability.
It is known to program a flight management computer to automatically trigger the sending of a data message when a preset value of a trigger threshold variable has been reached or exceeded. During each flight, a data message is transmitted every time the trigger threshold variable increases from a value below the preset value to a value equal to or exceeding the preset value.
Because the messaging service is typically provided by a data link service provider that is independent of the airline operating the aircraft, there is a communications cost to the airline associated with each message. Data link service providers use a variety of different air-to-ground data links (VHF, HF and satellite). As a flight progresses, the aircraft's mode of communication may change from VHF to HF or from VHF to SATCOM. When such a communication transition occurs, often the communication costs can greatly increase for the airline or data link service provider.
Previously, an arbitrary value was chosen and set prior to the aircraft departure. The value of the trigger threshold variable was not dynamically set per flight. Typically, one value was used for an aircraft type and airline and was not altered. This resulted in inefficient use of the aircraft communication assets as well as flight management computer processing resources.
An adaptive solution is needed that can reset or set the value of the trigger threshold variable to reduce, limit, schedule or increase aircraft communication based on the current aircraft environment and the current airline costs.